locks.c

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#include <linux/ceph/ceph_debug.h>

#include <linux/file.h>
#include <linux/namei.h>

#include "super.h"
#include "mds_client.h"
#include <linux/ceph/pagelist.h>

static int ceph_lock_message(u8 lock_type, u16 operation, struct file *file,
                 int cmd, u8 wait, struct file_lock *fl)
{
    struct inode *inode = file->f_dentry->d_inode;
    struct ceph_mds_client *mdsc =
        ceph_sb_to_client(inode->i_sb)->mdsc;
    struct ceph_mds_request *req;
    int err;
    u64 length = 0;

    req = ceph_mdsc_create_request(mdsc, operation, USE_AUTH_MDS);
    if (IS_ERR(req))
        return PTR_ERR(req);
    req->r_inode = inode;
    ihold(inode);

    /* mds requires start and length rather than start and end */
    if (LLONG_MAX == fl->fl_end)
        length = 0;
    else
        length = fl->fl_end - fl->fl_start + 1;

    dout("ceph_lock_message: rule: %d, op: %d, pid: %llu, start: %llu, "
         "length: %llu, wait: %d, type: %d", (int)lock_type,
         (int)operation, (u64)fl->fl_pid, fl->fl_start,
         length, wait, fl->fl_type);

    req->r_args.filelock_change.rule = lock_type;
    req->r_args.filelock_change.type = cmd;
    req->r_args.filelock_change.pid = cpu_to_le64((u64)fl->fl_pid);
    /* This should be adjusted, but I'm not sure if
       namespaces actually get id numbers*/
    req->r_args.filelock_change.pid_namespace =
        cpu_to_le64((u64)(unsigned long)fl->fl_nspid);
    req->r_args.filelock_change.start = cpu_to_le64(fl->fl_start);
    req->r_args.filelock_change.length = cpu_to_le64(length);
    req->r_args.filelock_change.wait = wait;

    err = ceph_mdsc_do_request(mdsc, inode, req);

    if ( operation == CEPH_MDS_OP_GETFILELOCK){
        fl->fl_pid = le64_to_cpu(req->r_reply_info.filelock_reply->pid);
        if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)
            fl->fl_type = F_RDLCK;
        else if (CEPH_LOCK_EXCL == req->r_reply_info.filelock_reply->type)
            fl->fl_type = F_WRLCK;
        else
            fl->fl_type = F_UNLCK;

        fl->fl_start = le64_to_cpu(req->r_reply_info.filelock_reply->start);
        length = le64_to_cpu(req->r_reply_info.filelock_reply->start) +
                         le64_to_cpu(req->r_reply_info.filelock_reply->length);
        if (length >= 1)
            fl->fl_end = length -1;
        else
            fl->fl_end = 0;

    }
    ceph_mdsc_put_request(req);
    dout("ceph_lock_message: rule: %d, op: %d, pid: %llu, start: %llu, "
         "length: %llu, wait: %d, type: %d, err code %d", (int)lock_type,
         (int)operation, (u64)fl->fl_pid, fl->fl_start,
         length, wait, fl->fl_type, err);
    return err;
}

int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
{
    u8 lock_cmd;
    int err;
    u8 wait = 0;
    u16 op = CEPH_MDS_OP_SETFILELOCK;

    fl->fl_nspid = get_pid(task_tgid(current));
    dout("ceph_lock, fl_pid:%d", fl->fl_pid);

    /* set wait bit as appropriate, then make command as Ceph expects it*/
    if (F_SETLKW == cmd)
        wait = 1;
    if (F_GETLK == cmd)
        op = CEPH_MDS_OP_GETFILELOCK;

    if (F_RDLCK == fl->fl_type)
        lock_cmd = CEPH_LOCK_SHARED;
    else if (F_WRLCK == fl->fl_type)
        lock_cmd = CEPH_LOCK_EXCL;
    else
        lock_cmd = CEPH_LOCK_UNLOCK;

    err = ceph_lock_message(CEPH_LOCK_FCNTL, op, file, lock_cmd, wait, fl);
    if (!err) {
        if ( op != CEPH_MDS_OP_GETFILELOCK ){
            dout("mds locked, locking locally");
            err = posix_lock_file(file, fl, NULL);
            if (err && (CEPH_MDS_OP_SETFILELOCK == op)) {
                /* undo! This should only happen if
                 * the kernel detects local
                 * deadlock. */
                ceph_lock_message(CEPH_LOCK_FCNTL, op, file,
                          CEPH_LOCK_UNLOCK, 0, fl);
                dout("got %d on posix_lock_file, undid lock",
                     err);
            }
        }

    } else if (err == -ERESTARTSYS) {
        dout("undoing lock\n");
        ceph_lock_message(CEPH_LOCK_FCNTL, op, file,
                  CEPH_LOCK_UNLOCK, 0, fl);
    }
    return err;
}

int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
{
    u8 lock_cmd;
    int err;
    u8 wait = 1;

    fl->fl_nspid = get_pid(task_tgid(current));
    dout("ceph_flock, fl_pid:%d", fl->fl_pid);

    /* set wait bit, then clear it out of cmd*/
    if (cmd & LOCK_NB)
        wait = 0;
    cmd = cmd & (LOCK_SH | LOCK_EX | LOCK_UN);
    /* set command sequence that Ceph wants to see:
       shared lock, exclusive lock, or unlock */
    if (LOCK_SH == cmd)
        lock_cmd = CEPH_LOCK_SHARED;
    else if (LOCK_EX == cmd)
        lock_cmd = CEPH_LOCK_EXCL;
    else
        lock_cmd = CEPH_LOCK_UNLOCK;

    err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
                file, lock_cmd, wait, fl);
    if (!err) {
        err = flock_lock_file_wait(file, fl);
        if (err) {
            ceph_lock_message(CEPH_LOCK_FLOCK,
                      CEPH_MDS_OP_SETFILELOCK,
                      file, CEPH_LOCK_UNLOCK, 0, fl);
            dout("got %d on flock_lock_file_wait, undid lock", err);
        }
    } else if (err == -ERESTARTSYS) {
        dout("undoing lock\n");
        ceph_lock_message(CEPH_LOCK_FLOCK,
                  CEPH_MDS_OP_SETFILELOCK,
                  file, CEPH_LOCK_UNLOCK, 0, fl);
    }
    return err;
}

void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
{
    struct file_lock *lock;

    *fcntl_count = 0;
    *flock_count = 0;

    for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
        if (lock->fl_flags & FL_POSIX)
            ++(*fcntl_count);
        else if (lock->fl_flags & FL_FLOCK)
            ++(*flock_count);
    }
    dout("counted %d flock locks and %d fcntl locks",
         *flock_count, *fcntl_count);
}

int ceph_encode_locks(struct inode *inode, struct ceph_pagelist *pagelist,
              int num_fcntl_locks, int num_flock_locks)
{
    struct file_lock *lock;
    struct ceph_filelock cephlock;
    int err = 0;
    int seen_fcntl = 0;
    int seen_flock = 0;

    dout("encoding %d flock and %d fcntl locks", num_flock_locks,
         num_fcntl_locks);
    err = ceph_pagelist_append(pagelist, &num_fcntl_locks, sizeof(u32));
    if (err)
        goto fail;
    for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
        if (lock->fl_flags & FL_POSIX) {
            ++seen_fcntl;
            if (seen_fcntl > num_fcntl_locks) {
                err = -ENOSPC;
                goto fail;
            }
            err = lock_to_ceph_filelock(lock, &cephlock);
            if (err)
                goto fail;
            err = ceph_pagelist_append(pagelist, &cephlock,
                       sizeof(struct ceph_filelock));
        }
        if (err)
            goto fail;
    }

    err = ceph_pagelist_append(pagelist, &num_flock_locks, sizeof(u32));
    if (err)
        goto fail;
    for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
        if (lock->fl_flags & FL_FLOCK) {
            ++seen_flock;
            if (seen_flock > num_flock_locks) {
                err = -ENOSPC;
                goto fail;
            }
            err = lock_to_ceph_filelock(lock, &cephlock);
            if (err)
                goto fail;
            err = ceph_pagelist_append(pagelist, &cephlock,
                       sizeof(struct ceph_filelock));
        }
        if (err)
            goto fail;
    }
fail:
    return err;
}

/*
 * Given a pointer to a lock, convert it to a ceph filelock
 */
int lock_to_ceph_filelock(struct file_lock *lock,
              struct ceph_filelock *cephlock)
{
    int err = 0;

    cephlock->start = cpu_to_le64(lock->fl_start);
    cephlock->length = cpu_to_le64(lock->fl_end - lock->fl_start + 1);
    cephlock->client = cpu_to_le64(0);
    cephlock->pid = cpu_to_le64(lock->fl_pid);
    cephlock->pid_namespace =
            cpu_to_le64((u64)(unsigned long)lock->fl_nspid);

    switch (lock->fl_type) {
    case F_RDLCK:
        cephlock->type = CEPH_LOCK_SHARED;
        break;
    case F_WRLCK:
        cephlock->type = CEPH_LOCK_EXCL;
        break;
    case F_UNLCK:
        cephlock->type = CEPH_LOCK_UNLOCK;
        break;
    default:
        dout("Have unknown lock type %d", lock->fl_type);
        err = -EINVAL;
    }

    return err;
}